Thermal conversion behaviors and products of spent mushroom substrate in CO2 and N2 atmospheres: kinetic, thermodynamic, TG and Py-GC/MS analyses

This study aims at characterizing pyrolysis/gasification behaviors and products of spent mushroom substrate (SMS) in the CO2 and N2 atmospheres. The major decomposition stages occurred between 200 and 600 °C with the mass losses of 60.4 and 61.5% at 20 °C/min in the CO2 and N2 atmospheres, respectively. The maximum mass loss rate grew with the increased heating rate, while DTG curves shifted toward a higher temperature. Volatiles were released easier in the N2 than CO2 atmosphere with a higher comprehensive devolatilization index and decomposition rate. At above 750 °C, the char gasification in the CO2 atmosphere resulted in a significant mass loss as well as a less char yield. Average activation energies by the Flynn-Wall-Ozawa method were estimated at 212 and 214 kJ/mol in the CO2 and N2 atmospheres, respectively. The higher thermodynamic parameters in the N2 than CO2 atmosphere indicated the higher reactivity of the pyrolysis in the N2 atmosphere. The reaction mechanisms of the volatiles decomposition were best described by g(α) = (1-α)-1-1 (R2 model) in the range of 200 to 370 °C in both atmospheres. The major pyrolysis products at 800 °C were identified using Py-GC/MS and composed mostly of aromatic compounds such as toluene and x-methyl-naphthalenes.

Source: Journal of Analytical and Applied Pyrolysis - February 10, 2019 Category: Chemistry Source Type: research